1. Field of the Invention
The present invention relates to a heat processing apparatus for heating a substrate such as a semiconductor wafer, when, for example, a photoresist is coated and developed.
2. Description of the Related Art
In the photolithography process for manufacturing a semiconductor device, a photoresist film is coated on a wafer, light-exposed in accordance with a prescribed circuit pattern, and developed.
Here, the photolithography process includes various heat processing such as pre-baking after the resist coating, post exposure baking after the light-exposure, and post-baking after the development.
These heat processing are executed in a heat processing apparatus, wherein the wafer is placed on or near the surface of a hot plate.
One of the conventional heat processing apparatus includes: a cover for covering a circumference of the hot plate; and a ceiling over the wafer, thereby forming a heat process space between the hot plate and the ceiling. The wafer is heated in an air which is introduced from outside of the heat processing apparatus, flows from the circumference of the hot plate to the center and is exhausted from the center of the ceiling. It is desired that the hot plate is heated uniformly in order to heat the wafer uniformly in this heat processing apparatus.
However, as the air flows from the circumference of the wafer to the center of the wafer, the heated air passing over the high temperature wafer is concentrated at the center of the wafer.
Therefore, the temperature of the wafer center is higher than that of the wafer circumference, even when the hot plate is uniformly heated.
An object of the present invention is to provide a heat processing apparatus which improves a uniformity in temperature on a surface substrate such as a wafer substrate.
The heat processing apparatus of the 1st invention comprises: a hot plate for putting the substrate on or near its surface; a ceiling with a first and second regions opposite to the hot plate surface; and a temperature control mechanism for controlling a regional temperature of at least one of the first and second regions, wherein the temperature control mechanism controls the regional temperature, in accordance with a temperature distribution of the substrate heated by the hot plate.
The heat processing apparatus of the 2nd invention comprises: a hot plate for putting the substrate on or near its surface; a ceiling with a first and second concentric regions opposite to the hot plate surface; a surrounding member for surrounding a space between the hot plate and the ceiling; gas flow generation means for generating a gas flow in the space from a circumference of the hot plate to a center of the ceiling, and a temperature control mechanism for controlling a regional temperature of the first region, wherein the temperature control mechanism controls the regional temperature in such a manner that a heat emission is greater from a center of the substrate than from a circumference of the substrate.
The heat processing apparatus of the 3rd comprises: a hot plate for putting the substrate on or near its surface; a ceiling with a first and second concentric regions opposite to the hot plate surface; a temperature control mechanism for controlling a regional temperature of the first region; and a heating mechanism for heating the second region, wherein the first region is opposite to a part of the substrate of which temperature is higher, while the second region is opposite to the rest of the substrate of which temperature is lower; the temperature control mechanism controls the regional temperature in such a manner that the regional temperature is lower in the first region than in the second region, and the heating mechanism heats the second region up to a prescribed temperature in accordance with a temperature at a part of the substrate opposite to the second region.
The heat processing apparatus of the 4th comprises: a hot plate for putting the substrate on or near its surface; a ceiling with a first and second concentric regions opposite to the hot plate surface; a surrounding member for surrounding a space between the hot plate and the ceiling; gas flow generation means for generating a gas flow in the space from a circumference of the hot plate to a center of the ceiling; a temperature control mechanism for controlling a regional temperature of the first region, and a heating mechanism for heating the second region, wherein: the temperature control mechanism controls the regional temperature in such a manner that the regional temperature is lower in the first region than in the second region; and the heating mechanism heats the second region in accordance with a temperature of a part of the substrate opposite to the second region.
According to the 1st invention, the temperature becomes uniform all over the substrate, by promoting a heat emission from a hotter portion of the substrate, because the first region opposite to the hotter portion of the substrate is made cooler than the second region, thereby increasing a heat absorption by the first region. Further, the temperature uniformity on the substrate surface is improved by controlling the cooling of the first region by the temperature control mechanism.
Further, according to the 2nd invention, the temperature uniformity on the substrate surface is improved, particularly when the substrate is heated in a gas flow from the circumference to the center of the hot plate, because there are provided first and second concentric regions on the ceiling, wherein the temperature of first region is controlled as in the 1st invention.
Further, according to the 3rd invention, the temperature becomes quite uniform all over the substrate, by promoting a heat emission from a hotter portion of the substrate, because the first region opposite to the hotter portion of the substrate is made cooler than the second region, thereby increasing a heat absorption by the first region, and at the same time the second region is heated by the heating mechanism, thereby suppressing a heat radiation from the cooler portion of the substrate.
Further, according to the 4th invention, the temperature uniformity on the substrate surface is improved, particularly when the substrate is heated in a gas flow from the circumference to the center of the hot plate, because there are provided first and second concentric regions on the ceiling, wherein the temperature of first and second regions are controlled as in the 3rd invention.
Further, in the 1st to 4th inventions, a heat pipe may be employed, in order to make the temperatures of each region uniform and rapidly stabilize it due to a rapid transportation of a great deal of heat by the heat pipe.
Further, in the 1st to 4th inventions, it is preferable that the heat absorption of the first region is higher than that of the second region in order to promote the heat emission from the hotter portion of the substrate, thereby improving the temperature uniformity more rapidly. Therefore, The first region may preferably a black body, while the second region may preferably a mirror.